Process for preparing interpolymers of carbon monoxide and ethylenically unsaturated compounds

ABSTRACT

High molecular weight, crystalline interpolymers of carbon monoxide with one or more unsaturated compounds such as aliphatic monoolefins are prepared by reacting carbon monoxide with said unsaturated compounds in the presence of catalyst consisting essentially of HPd(CN)3. Novel high molecular weight, crystalline interpolymers of carbon monoxide and unsaturated monoolefins, particularly ethylene, having alternating   AND -C2H4- units, are described.

United States Patent [1 1 [111 3,835,123 Nozaki Sept. 10, 1974 [54] PROCESS FOR PREPARING 3,689,460 9/1972 Nozaki 260/63 INTERPOLYMERS OF CARBON 3,694,412 9/1972 Nozaki 260/63 I MONOXIDE AND ETHYLENICALLY UNSATURATED C M D Primary Examiner-Lester L. Lee

Art ,A t, F" -N E.F [75] Inventor: Kenzie Nozaki, St. Louis, Mo. Omey gen or Oms armger [73] Assignee: Shell Oil Company, Houston, Tex. [57] ABSTRACT [22] Filed: 26, 1973 High molecular weight, crystalline interpolymers of 2 APPL 344,679 carbon monoxide with one or more unsaturated compounds such as aliphatic monoolefins are prepared by reacting carbon monoxide with said unsaturated com- [52] 260/94'9 260/63 CQ, 260/94-9 pounds in the presence of catalyst consisting essen- 260/DIG- 43 tially of l-lPd(CN) Novel high molecular weight, [51] Int. Cl. C08f 1/64, C08f 13/04 crystalline interpolymers of carbon monoxide and [58] F'eld of Search 260/63 CQ, R, saturated monoolefins, particularly ethylene, having zo/DIG- 43 ,e fieweiinsl [56] References Cited 0 UNITED STATES PATENTS 1; 2,441,082 5/1948 Pinkney 260/67 a v. ,3 .r v 2,495,282 l/l950 Pinkney 260/67 and C2H4 units, are described 2,495,286 H1950 Brubaker 260/63 3,530,109 9/1970 Fenton 260/94.9 7 Claims, No Drawings 1 PROCESS FOR PREPARING INTERPOLYMERS OF CARBON MONOXIDE AND ETI-IYLENICALLY UNSATURATED COMPOUNDS BACKGROUND OF THE INVENTION able catalyst including peroxy compounds such as benzoyl peroxide (Brubaker U.S. Pat. No. 2,495,286) and alkyl phosphine complexes of palladium salts such as tributyl phosphine complexes (ICI British Pat. No. 1,081,304).

Ethylene-carbon monoxide copolymers have also been prepared by radiation initiated copolymerizing. See, for example, Co y-Radiation Induced Copolymerization of Ethylene and Carbon Monoxide, P. Columbo et al., Journal of Polymer Science: Part A-l, Vol. 4, Pages 29-57 (1966).

In general, the use of peroxy catalysts requires high pressures, i.e., above 500 atmospheres and, on occasion, up to 3,000 atmospheres in order to prepare solid polymers. Thus, normally solid ethylene/carbon monoxide copolymers must be prepared at pressures from about 500 atmospheres (7,500 psi) to 1,000 atmospheres (15,000 psi). Also, it is generally necessary, in order to prepare solid polymers, to employ peroxy catalysts which are free of any F riedel-Crafts catalysts thus severely limiting their use. Furthermore, the use of peroxy catalysts results in low molecular weight polymers having a random distribution of enchained comonomers.

The use of alkyl phosphine complexes of palladium salts requires high temperatures, i.e., greater than 120C and relatively high pressures, i.e., greater than 2,000 psi. It is also known that these alkyl phosphine complex catalysts, even at such elevated temperatures and pressures, still have relatively low reactivity, i.e., low yields of polymers. The use of alkyl phosphine complexes produces polymers having a random distribution.

Cyano-containing compounds of palladium and their preparation, are generally known. See, for example, the preparation of l-I Pd(CN), by reacting K Pd(CN)., with concentrated I-ICl [D. F. Evans et al., J.C.S., 3,167 (1964)]. It is also known that Pd(CN) is an effective catalyst for preparing ethylene-carbon monoxide copolymers. See, for example, US. Pat. No. 3,530,109.

While the copolymers prepared using Pd(CN) have relatively high molecular weight, the yields are low and the resulting copolymers are grey water-insoluble solids. Also, the catalyst residues in the polymer are generally difficult to remove.

It has now been discovered that high molecular weight, linear, crystalline, nearly white interpolymers of carbon monoxide and ethylenically unsaturated monomers, such as ethylene, can be prepared in high yield when a catalyst consisting essentially of HPd(CN) is employed.

This novel catalyst, HPd(CN) and its preparation is the subject matter of copending Pat. applicatiomSer. No. 344,680 filed Mar. 26, 1973.

SUMMARY OF THE INVENTION The present invention provides an improved process for preparing in high yield linear, high molecular weight l0,000), crystalline, nearly white, waterinsoluble, interpolymers of carbon monoxide and a copolymerizable ethylenically unsaturated comonomer,

particularly a monoolefin, and more particularly ethylene, having an alternating 1:1 ratio of carbon monoxide and comonomer.

DESCRIPTION OF THE PREFERRED EMBODIMENTS stood that one or more other suitable ethylenically unsaturated organic compounds may be employed.

By ethylenically unsaturated organic compounds is meant those compounds which contain a linkage.

Examples of suitable unsaturated compounds coming within the scope of the present invention include the monoolefins, preferably containing from about two to eight carbon atoms such as ethylene, propylene, butylene, isobutylene, and pentylene; diolefins such as butadiene, isoprene, and 2-chlorobutadiene-1,3; vinylidene compounds such as vinylidene chloride; tetrafluoroethylene; vinyl halides, esters and acetals, such as vinyl acetate, vinyl chloride, vinyl chloroacetate, vinyl dimethylacetate, and vinyl trimethylacetate; vinyl ketones such as vinyl methyl ketone and vinyl ethyl ketone; vinyl hydrocarbons such as styrene, chlorostyrene and alphamethyl styrene; acrylic and methacrylic acids, esters, amides, nitriles and acid halides; and vinyl esters of unsaturated carboxylic acids such as vinyl hexenoate, vinyl crotonate, etc. The above listing is not exhaustive and is presented as representative. Other unsaturated compounds will be apparent to one skilled in the art.

Preferred ethylenically unsaturated compounds include the monoolefins, particularly the alpha-olefins, having from two to eight carbon atoms. Particularly preferred is ethylene.

Copolymers prepared by the instant process have the wherein R is the residue of the copolymerizable monomer and n is an integer having a value of from about 200 to 40,000 or expressed in another way, n has a value commensurate with a total molecular weight of roughly 10 to 2 X 10 The above alternating structure was confirmed by NMR measurements. The molecular weight of the resulting polymers was estimated from intrinsic viscosity measurements of polymer solutions in meta-cresol and hexafluoroisopropanol I-IF I PA It will be appreciated that R may represent residues of different monomers in the same interpolymer when two or more comonomers are employed. Thus, if a mix- 3. ture of ethylene and propylene were employed, a representative idealized structural formula would be:

l s lu wherein n has an appropriate value as noted above, e.g., to produce a mol weight of 10 to 2 X 10 The preferred interpolymer is an interpolymer of carbon monoxide and ethylene having the following formula:

wherein n has the value as noted above, and preferably from about 10 to 10.

The catalyst utilized in the present process consists essentially of HPd(CN) This novel catalyst, HPd(CN) and its preparation by several methods is described in detail in copending Pat. application, Ser. No. 344,680, filed Mar. 26,. i973.

One method for preparing HPd(CN) comprises (1) contacting Pd(CN) with an aqueous solution of HCN in molar excess for a time and temperature sufficient to effect the desired reaction, and (2) evaporating the resulting reaction mixture to dryness under reduced pressure (in vacuo) at a temperature of from about to 40C, and preferably about 20-30C, and (3) recovering the white, water-soluble HPd(CN) residue.

In general, Pd(CN) is treated with an excess aqueous solution of HCN for a few minutes to several days at temperatures ranging from about 0 to 100C. Preferably, the reaction is performed at temperatures from about 70 to 90C for periods ranging from about /2 to 5 hours. lt will be appreciated that lower temperatures require longer reaction times and higher temperatures allow much shorter reaction times.

As stated hereinbefore, the l-lCN is utilized in excess and as an aqueous solution. A 100 to 500 percent stoichiometric excess is usually adequate, however, a greater or lesser excess may be employed as desired. In general, the HCN is employed as a l to percent aqueous solution. A very suitable reaction procedure comprises reacting Pd(CN) with a 200 percent excess of a 5 percent aqueous solution of HCN for l-3 hours at 70 to 90C.

After the desired reaction is completed, reaction product is recovered by evaporating the solution to dryness in vacuo. The water and excess HCN is thereby removed by applying reduced pressure, i.e., a vacuum of less than about 10 mm of mercury at temperatures less than about 25C. The resulting product is a watersoluble white powder analyzed as HPd(CN) Another method for preparing HPd(CN) comprises l contacting an aqueous solution of K Pd(CN)., with a conventional acid-type cation exchange resin in the acid form, (2) evaporating the resulting solution to dryness in vacuo at a temperature of from about 0 to 40C and (3) recovering the white, water-soluble l-lPd(CN) residue.

Any cation exchange resin is suitable for use in the instant method so long as it is in the acid form. Cation exchange resins are well known and are commercially available from a number of manufacturers under a multitude of trade designations. For a more detailed description of the theory, preparation and regeneration of cation exchange resins, see lon Exchange, Helfferich, McGraw-Hill Book Company, Inc. (1962), particularly pages 29-47, and Ion Exchange Resins" Kunin, John Wiley and Sons, Inc., Second Edition 1958), particularly pages 82-97.

As noted hereinbefore, any cation exchange resin can be employed to prepare the instant catalyst; however, excellent results are obtained when the cation exchange resin is a sulfonic acid cation resin, a carboxylic-type cation resin, a'sulfonated phenolic cation resin, a carboxylic sulfonic resin as well'as the phosphoric, phosphonic and phosphorus acid resins and aluminum silicate resins. All these types are commercially available.'For a list of the major commercially available cation exchange resins, see Ion Exchange Resins, Kunin, John Wiley and Sons, Inc. Second Edition (1958), Table 13. In addition, the patent literature is replete with descriptions of the preparation of suitable cation exchange resins. See, for example, US. Pat. Nos. 2,860,109,; 2,877,191; 2,885,371; 2,891,014; 2,898,311; 3,030,317; and 3,275,575, among many others.

An aqueous solution of K Pd(CN), is simply contacted with a suitable cation exchange resin resin for a period of time which is sufficient to exchange the K ion for the l-l ion. In general, a 1 to 25 percent by weight aqueous solution of K Pd(CN) solution is contacted with the cation exchange resin for l to 24 hours at temperatures from about 10 to 100C for A; to 10 hours.

The resulting solution is then placed under reduced pressure (in vacuo) and all the water and volatile material removed as hereinbefore described. The resulting product is a water-soluble, white powder analyzed as HPd(CN) Although pure l-lPd(CN) is the preferred catalyst, it may be desirable to utilize a catalyst blend or mixture which contains a major amount of HPd(CN in order to prepare essentially pure l-lPd(CN) it is essential, even critical, to perform the evaporation step under re duced pressure (in vacuo) at a temperature between about 0C and 40C. At temperatures above about 40C, the resulting catalyst product is a mixture of HPd(CN) and other Pd compounds, believed to be essentially Pd(CN) It should therefore be appreciated that if the catalyst is prepared at temperatures above about 40C, i.e., from about 40 to C, the resulting residue is not pure HPd(CN) but a blend consisting essentially of HPd(CN) It should be further appreciated that this mixture is still a more effective catalyst than Pd(CN) alone in that the yield of polymer per gram of catalyst is higher. Also, copolymers of carbon monoxide and ethylene prepared by the instant process utilizing such catalyst blend or mixtures are white to grey, water insoluble copolymers. Furthermore, the catalyst residues in the polymers are more easily removed when such mixtures are employed than when Pd(CN) is utilized alone.

The pure, or essentially pure, HPd(CN) is the preferred catalyst.

In general, the amount of catalyst will vary from as little as about 0.001 percent to as much as 5 percent by weight based on the total monomers charge. In most instances, for a number of reasons, it is generally preferable to utilize the minimum quantity of catalyst consistent with the desired purity, yield, conversion, etc; however, amounts from about 0.005 to about 1 percent have been found suitable for most applications.

The polymerization of the carbon monoxide with the ethylenically unsaturated compound can be carried out either in a batch, semi-continuous or continuous process wherein the catalyst and the monomers are first charged into a suitable reaction vessel. The mixture is then generally heated either under autogeneous pressure or under superatmospheric pressure until the degree of polymerization is achieved.

The polymerizaion may be performed in vessels constructed or lined with glass, steel, copper, aluminum, silver, stainless steel, etc.; however, stainless steel, or other inert metals are preferred.

In general, the polymerization process is performed at temperatures ranging from about 75 to 150C and at pressures from slightly above atmosperhic pressure to 1,000 atmospheres.

It is preferred, however, to utilize temperatures of from about 75 to 125C and pressures from about to 1,000 atmospheres with from 25 to 150 atmospheres pressure being especially preferred.

In order to achieve acceptable catalyst activity and reaction rates, it is not essential that the copolymerization be performed in the presence of -a solvent or reaction media; however, under some circumstances, it may be desirable to employ one or more suitable media.

Suitable media include water or any other normally liquid, non-polymerizable, preferably volatile organic compounds including the aromatic and saturated acyclic and alicyclic hydrocarbons, ethers, esters, alcohols, amines, ketones, halogenated hydrocarbons, etc. Suitable such solvents include among others, benzene, toluene, xylene, isooctane, cyclohexane, formamide, pyridine, ethyl acetate, etc.

Especially suitable solvents include the nitrogencontaining solvents, particularly nitriles, such as acetonitrile.

In general, the monomers may be introduced into the reactor in a wide range of ratios. Preferably, however, it is highly desirable to use an excess of comonomers to the carbon monoxide. Thus, a very suitable mole ratio of ethylene to carbon monoxide is from about 1:1 to 50:1 with from about 10:1 to :1 being preferred.

The following examples are presented in order to il lustrate the process of the present invention. It is understood, however, that the examples are for the purpose of illustration only and that the invention is not to be regarded as limited to any of the specific conditions or reactants recited therein. Unless otherwise indicated, parts described in the examples are parts by weight. Pressure measurements are at ambient (room) temperatures.

EXAMPLE 1 This example illustrates the preparation of HPd(CN) via the Pd(CN) -aqueous HCN method.

One gram of Pd(CN) and 100 ml of a 4%w aqueous solution of HCN were added to a 200 ml tantalum pressure vessel. The Pd(CN) turned white and partially dissolved. The vessel was closed and it was heated with agitation for 4 hours at 90C. The vessel and contents were cooled to room temperature, the vessel opened and the colorless, clear solution was removed. The solution was evaporated to dryness in a rotating evaporator in vacuo (ca 1 mm Hg) at room temperature (22C). 1.16g of a white, water-soluble residue was obtained, which was handled in a dry box.

Elemental analysis of the residue was consistent with the formula HPd(CN) (Found: 19.0% C, 22.4% N, 0.60% H, 57.0% Pd. Calculated for HPd(CN) 19.3% C, 22.6% N, O.54% H, 57.7% Pd). The recovery of product (1.16g) was very close to the theoretical (1.17g). Aqueous solutions of the compound were highly acidic (pKa 2.3) and potentiometric titrations showed 0.9 to 1.1 protons per palladium.

EXAMPLE n This example illustrates the preparation of HPd(CN) via the ion-exchange method.

1.2g of K Pd(CN) was dissolved in 15 ml of distilled water and 10g of acidic ion exchange resin (Amberlite IR 1201-1) was added. After stirring for 3 hours, the resin was filtered off and replaced. This was repeated five times. The solution was evaporated to dryness in a rotating evaporator in vacuo at room temperature. A white residue was obtained which weighed 0.77g. It analyzed for 57.3% Pd (theory is 57.7%), and titration with NaOH indicated 1.02 protons per palladium.

EXAMPLE III This example illustrates the preparation of an ethylene-carbon monoxide copolymer using the instant novel catalyst HPd(CN) Into a 600 ml tantalum reactor was added 0.025 g of HPd(CN) prepared in Example I, 50 ml of dried cyclohexane, 7g of glass beads, psig of carbon monoxide and 850 psig of ethylene. The reactor and contents were heated and shaken at C for 18 hours. After cooling, depressuring, opening the reactor, and separating the beads and solvent, g of a white polymer melting at about 260C and analyzing for 64.2%w C, 7.2%w H and 28.6%w 0 were obtained.

Under similar conditions, 0.025g of HPd(CN) prepared according to Example 11 yielded 13.4g of polymer and 0.021 g of Pd(CN) yielded 4.7g of polymer. NMR analyses confirmed that the polymers had an alternating -C l-l and StI'UCtLl 1'6 EXAMPLE IV This example illustrates the superiority of HPd(CN) over Pd(CN) as a catalyst for the copolymerization of ethylene and carbon monoxide.

Into a 600 ml tantalum reactor were placed 7g of glass beads, 50 ml of cyclohexane, 850 psig of ethylene, 100 Psig of carbon monoxide (at 20C), and various amounts of Pd(CN) l-lPd(CN) prepared as in Example 1 (ex aq HCN), and HPd(CN),-, prepared as in Example H (ex cation exchange resin). The results are as follows:

Catalyst 8 Max a g Copoly. Ppe siirre Copolymer '65- I. 6

g m r g Solvent psig g dl/g (m-cresol) si p 2 None 1825 17.9 5.02 1301010 0.021 1620 18 105 47 g y 9 3-2 Pd(CN) (1.15. 0.025 1500 1a 105 13.4 Hr urdrcm (aq HCN) 0.025 1550 18 105 13.5 g f HPd(CN),(I.E.) 0.025 1700 s 115 10.8 28 2157 HPd(CN) (aq HCN) 0.025 1725 s 115 11 4 f g g 1840 136 if;

Chioroform 1550 14.0 5:30 n- Hexane 1600 15.7 4.80

The above data clearly illustrate that significant 1Q ggg ggl l hlgher yields of copolymer are obtamed m a given pe Methyt my] keme 1675 19.7 mod of tune when the catalyst is HPd(CN) Ethyl acetate 1700 20.1 5.38

EXAMPLE V This example illustrates the preparation of several 15 EXAMPLE VII C H CO copolymers utilizing HPd(CN) prepared at A r various HCN concentrations, times, temperatures, etc. This example illustrates the preparation of other olefin-carbon monoxide copolymers.

Into a ml stainless steel reactorequipped with a o a 50 m1 Stainless ee T equipp With magnetic stirrer were added Pd(CN) and various 2O magnetic stirring were placed various catalysts, olefins amounts of 11Pd(CN) prepared a h i b f 1 and carbon monoxide. The results of representative exscribed, 0 psig of ethylene and psig of: carbon perimental runsareastollows:

Olefin Pressr CO Tim Temp. Yield l.V. (dl/g Catalyst Olefin psig" Psig Hr. "G g in m-Cresol) M.P.C

0.053 Pd(CN), C l-i, 850 100 94 65 0.287 093 200-120 0.053 HPd(CN) C l-1 -850 100 65 0.65 0.60 190-220 0.025g HPd(CN) Btutene-l 850 150 18 0.03 0.025g HPd(CN) Norbornylene 2g 150 18 115 0.014

"Pressures at room temperature,

monoxide (at 20C). The reactor was heated to 95C with stirring. After 18 hours at 95C, the polymer residue was recovered. The results of representative experme u tabula edinTabls TABLE I l ciaim as my invention: v

l. A process for preparing high molecular weight, linear interpolymers of carbon monoxide with at least one alpha-olefin having from two to eight carbon atoms in all experimental runs, polymers prepared with Pd(CN) were grey, whereas polymers prepared with HPd(CN) were white.

EXAMPLE V1 This example illustrates the preparation of copolymers of C H and CO in the presence of i1Pd(C1-I) uti- 55 lizing a number of solvents. The HPd(CN) was prepared in situ from 0.075 grams of Pd(CN)- and 1.5 moles of HCN per mole of Pd(CN) which comprises reacting 1 mole of carbon monoxide with from about 1 to about 50 moles of alpha-olefin at about 75C to about 150C and about 10 to about 1,000 atmosphere pressures in the presence of a cataiytic amount of a catalyst consisting essentially of l-lPd(CN) 2. A process as in claim 1 wherein the carbon monoxide to alpha olefin is employed in a mole ratio of from about 1:5 to about 1:25.

3. A process as in claim 1 wherein the alpha-olefin is ethylene.

4. A process as in claim 1 wherein the reaction temperature is from about 75 to C.

5. A process as in claim 1 wherein an inert organic 60 medium is employed.

6. A process as in claim 5 wherein the medium is a nitrogen-containing hydrocarbon.

7. A process as in claim 6 wherein the hydrocarbon is acetonitrile. 

2. A process as in claim 1 wherein the carbon monoxide to alpha olefin is employed in a mole ratio of from about 1:5 to about 1:
 25. 3. A process as in claim 1 wherein the alpha-olefin is ethylene.
 4. A process as in claim 1 wherein the reaction temperature is from about 75* to 125*C.
 5. A process as in claim 1 wherein an inert organic medium is employed.
 6. A process as in claim 5 wherein the medium is a nitrogen-containing hydrocarbon.
 7. A process as in claim 6 wherein the hydrocarbon is acetonitrile. 